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This has long been a temptation for engineers. 40 years ago the textbook in the digital electronics class I took at Caltech had a chapter called "The Engineer a

by tzs 3y ago

This has long been a temptation for engineers. 40 years ago the textbook in the digital electronics class I took at Caltech had a chapter called "The Engineer as Dope Pusher" that talked about it. It gave as an example clothes dryers. The way most home clothes dryers working back then was you put the clothes in, you turn a dial on a timer to the number of minutes you want the dryer to run, and you press start. The mechanical timers were very reliable. There hadn't been any substantial improvement in their design in decades because there really wasn't anything to improve. There had been improvement in the materials used, and in the cost, but fundamentally mechanical timers was a solved problem. If the mechanical timer ever broke the repairperson would have replacements in their van. Even if they didn't have the specific one for your dryer it didn't matter because they all worked pretty much the same. They could just put in another one. Maybe the mounting holes wouldn't be in the right place, but they could easily improvise some way to mount it in your dryer. The book went on to say that somewhere there is an engineer designing a new clothes dryer, and instead of a mechanical timer that engineer is putting in a digital timer. It has a microprocessor, 7 segment LED digit displays for the time, some buttons for interacting with it (such as setting the time and correcting mistakes), and a power supply. And let's not forget that it has software. That digital timer has no advantage to the user over a mechanical timer. But it has disadvantages. The interface will be worse. It will cost more. It won't be more reliable and possibly will be less reliable, and if it does need repair the repairperson probable won't have the parts. If they have another brand's digital timer on hand they probably won't be able to adapt it to your dryer. So why is that engineer designing the new dryer with a digital timer? Because mechanical timers are boring. Digital electronics was at the cutting edge of consumer engineering then, and so by using a digital timer the engineer got to play with exciting new technology.

nuancebydefault 3y ago
What do you mean by "reliable" wrt mechanical timers? I'm pretty sure the clothing dryer is a harsh environment for such a component (moisture and heat can easily cause corrosion and mechanical stress). Also, I guess timing gets less accurate over time. If there are rubbers preventing moisture from entering and oil from leaving, those rubbers will wear out.
- purpleflame1257 3y ago
  The timer for the dryer is typically located outside of the dryer drum itself. It is not an actuating component.
- Fatnino 3y ago
  Like another commenter said, the timer is segregated from the harsh dryer environment. But also, some slop in the timing accuracy is just fine. The user doesn't really know how long precisely the drier needs to run to dry their clothes. They just know that if they set this timer to 45 then the clothes come out dry.
- beezlewax 3y ago
  I have one that is like 40 years old. The heating element is similar to those in an oven. The only things that broke are plastic door hinges.
mrguyorama 3y ago
Ah yes, the mythical world where engineers are in charge of deciding which features ship instead of management.
conradev 3y ago
> If the mechanical timer ever broke the repairperson would have replacements in their van > That digital timer has no advantage to the user over a mechanical timer. But it has disadvantages. The mechanical timer is known to degrade over time, which is why the repair person has spares in their van. Does the digital timer really have no advantages? Will it ever fail and need to be replaced? How much more does it cost? Yes, engineers are tempted to use shiny tools all of the time. Evaluating whether or not the tool is right for the job is _hard_. But it feels wrong to say that novelty is the only motivation behind upgrading tools? The digital timer was made by an engineer, too, who designed it to be a more reliable replacement for faulty mechanical timers. It has both advantages and disadvantages compared to mechanical timers, which is why the engineer made it in the first place?
- JadeNB 3y ago
  > The mechanical timer is known to degrade over time, which is why the repair person has spares in their van. Does the digital timer really have no advantages? Will it ever fail and need to be replaced? How much more does it cost? Surely the expected lifetime of a digital timer is shorter than that of a mechanical timer.
  - error503 3y ago
    Surely is a very strong statement here. I see no reason that a properly designed electronic timer wouldn't have effectively infinite lifetime, which is not possible with a practical mechanical timer. It has no moving parts (other than switches, which can be substituted for capacitive touch). A mechanical timer has many small mechanical parts and wear points, and can get gummed up over time if it doesn't outright stop functioning. In practice, cost engineering is going to mean neither is completely reliable, but it should be cheaper to make an electronic timer reliable enough. Especially today, where the cost of a functioning mechanical timer is probably an order of magnitude more than an equivalent electronic timer.
    - JadeNB 3y ago
      I'm willing to believe that the best electronic switches can last longer than the best mechanical switches, but there's so many more ways for an electronic switch to fail that it's a lot easier for me to trust an off-the-shelf mechanical switch than an off-the-shelf electronic one, especially if the cost of failure of the mechanical switch is just an easy swap in of another one.
Kirby64 3y ago
Mechanical timers are fine, but digital circuitry is by far going to be more reliable if designed properly. There isn't anything physically moving, so the failure modes are much more restrictive. Also, digital provides advantages with offering variable timing on a dryer, for instance, based on the input of a moisture sensor. Mechanical methods for that are more complicated. Additionally, I would be very surprised if the digital solution is not cheaper to make. Maybe not when first originally introduced, but nowadays it very likely is. You're right that repair-ability is hurt in some ways... but the industry has moved to compensate. You can buy boards and replace them. They aren't inherently hard to service, because the form factor doesn't really have limitations.
- joelfried 3y ago
  There is something physically moving: the machine itself. You can't wash or dry clothing without moving it around. Given that the entire machine moves (and on spin cycles, reasonably quickly), you need to make sure your circuitry is capable of handling the strain. As a homeowner, I wish someone (anyone!) still sold reliable analog appliances that just did their job simply and made repair parts and schematics reasonably available.
  - adolph 3y ago
    I do minor appliance repairs on occasion and the current time of manuals, videos and parts availablity feels like a golden age. Granted, none of my large appliances are younger than 10 years, but I think I could build new ones (expensively) for the all the parts and schematics available, even wiring diagrams.
  - Kirby64 3y ago
    Nobody would attach the timer to the actual moving drum, so the worst it has to deal with is physical vibrations from use (which, admittedly, can be quite violent if you have an unbalanced load). There are very few digital circuits that are actually meaningfully sensitive to vibrations. At worst, it's a manufacturing problem to make sure the PCB/solder joints don't crack from vibration. In comparison, the mechanical timer is physically moving. A clockspring, or some sort of mechanism that physically sets the time remaining. Depending on how it's built, vibrations are a harder problem to solve. Not impossible, obviously, but it certainly adds cost. Also, for most appliances we deal with today... they usually ARE simple to work on. Simple switches and mechanical contrivances. Parts are typically readily available... even PCBs, although possibly not at great pricing. There's certain appliances where you are basically screwed (fridges come to mind...), but that is mainly in my view because the typical failing part is the compressor. Nobody is rebuilding a compressor themselves.
cj 3y ago
I wish there were an easy way to screen these type of engineers out in the hiring process. It's very hard to judge whether a candidate's excitement over new technology is simply showing passion for what they do or a red flag. A certain degree of passion is desirable, but too much is not. The worst engineers I've worked with are ones who, in their first week, fall behind on their onboarding plan because the company's compiler needs a rewrite.

by tzs 3y ago

nuancebydefault 3y ago

What do you mean by "reliable" wrt mechanical timers? I'm pretty sure the clothing dryer is a harsh environment for such a component (moisture and heat can easily cause corrosion and mechanical stress). Also, I guess timing gets less accurate over time. If there are rubbers preventing moisture from entering and oil from leaving, those rubbers will wear out.

purpleflame1257 3y ago
The timer for the dryer is typically located outside of the dryer drum itself. It is not an actuating component.
Fatnino 3y ago
Like another commenter said, the timer is segregated from the harsh dryer environment. But also, some slop in the timing accuracy is just fine. The user doesn't really know how long precisely the drier needs to run to dry their clothes. They just know that if they set this timer to 45 then the clothes come out dry.
beezlewax 3y ago
I have one that is like 40 years old. The heating element is similar to those in an oven. The only things that broke are plastic door hinges.

mrguyorama 3y ago

Ah yes, the mythical world where engineers are in charge of deciding which features ship instead of management.

conradev 3y ago

> If the mechanical timer ever broke the repairperson would have replacements in their van > That digital timer has no advantage to the user over a mechanical timer. But it has disadvantages. The mechanical timer is known to degrade over time, which is why the repair person has spares in their van. Does the digital timer really have no advantages? Will it ever fail and need to be replaced? How much more does it cost? Yes, engineers are tempted to use shiny tools all of the time. Evaluating whether or not the tool is right for the job is _hard_. But it feels wrong to say that novelty is the only motivation behind upgrading tools? The digital timer was made by an engineer, too, who designed it to be a more reliable replacement for faulty mechanical timers. It has both advantages and disadvantages compared to mechanical timers, which is why the engineer made it in the first place?

JadeNB 3y ago
> The mechanical timer is known to degrade over time, which is why the repair person has spares in their van. Does the digital timer really have no advantages? Will it ever fail and need to be replaced? How much more does it cost? Surely the expected lifetime of a digital timer is shorter than that of a mechanical timer.
- error503 3y ago
  Surely is a very strong statement here. I see no reason that a properly designed electronic timer wouldn't have effectively infinite lifetime, which is not possible with a practical mechanical timer. It has no moving parts (other than switches, which can be substituted for capacitive touch). A mechanical timer has many small mechanical parts and wear points, and can get gummed up over time if it doesn't outright stop functioning. In practice, cost engineering is going to mean neither is completely reliable, but it should be cheaper to make an electronic timer reliable enough. Especially today, where the cost of a functioning mechanical timer is probably an order of magnitude more than an equivalent electronic timer.
  - JadeNB 3y ago
    I'm willing to believe that the best electronic switches can last longer than the best mechanical switches, but there's so many more ways for an electronic switch to fail that it's a lot easier for me to trust an off-the-shelf mechanical switch than an off-the-shelf electronic one, especially if the cost of failure of the mechanical switch is just an easy swap in of another one.

Kirby64 3y ago

Mechanical timers are fine, but digital circuitry is by far going to be more reliable if designed properly. There isn't anything physically moving, so the failure modes are much more restrictive. Also, digital provides advantages with offering variable timing on a dryer, for instance, based on the input of a moisture sensor. Mechanical methods for that are more complicated. Additionally, I would be very surprised if the digital solution is not cheaper to make. Maybe not when first originally introduced, but nowadays it very likely is. You're right that repair-ability is hurt in some ways... but the industry has moved to compensate. You can buy boards and replace them. They aren't inherently hard to service, because the form factor doesn't really have limitations.

joelfried 3y ago
There is something physically moving: the machine itself. You can't wash or dry clothing without moving it around. Given that the entire machine moves (and on spin cycles, reasonably quickly), you need to make sure your circuitry is capable of handling the strain. As a homeowner, I wish someone (anyone!) still sold reliable analog appliances that just did their job simply and made repair parts and schematics reasonably available.
- adolph 3y ago
  I do minor appliance repairs on occasion and the current time of manuals, videos and parts availablity feels like a golden age. Granted, none of my large appliances are younger than 10 years, but I think I could build new ones (expensively) for the all the parts and schematics available, even wiring diagrams.
- Kirby64 3y ago
  Nobody would attach the timer to the actual moving drum, so the worst it has to deal with is physical vibrations from use (which, admittedly, can be quite violent if you have an unbalanced load). There are very few digital circuits that are actually meaningfully sensitive to vibrations. At worst, it's a manufacturing problem to make sure the PCB/solder joints don't crack from vibration. In comparison, the mechanical timer is physically moving. A clockspring, or some sort of mechanism that physically sets the time remaining. Depending on how it's built, vibrations are a harder problem to solve. Not impossible, obviously, but it certainly adds cost. Also, for most appliances we deal with today... they usually ARE simple to work on. Simple switches and mechanical contrivances. Parts are typically readily available... even PCBs, although possibly not at great pricing. There's certain appliances where you are basically screwed (fridges come to mind...), but that is mainly in my view because the typical failing part is the compressor. Nobody is rebuilding a compressor themselves.

cj 3y ago

I wish there were an easy way to screen these type of engineers out in the hiring process. It's very hard to judge whether a candidate's excitement over new technology is simply showing passion for what they do or a red flag. A certain degree of passion is desirable, but too much is not. The worst engineers I've worked with are ones who, in their first week, fall behind on their onboarding plan because the company's compiler needs a rewrite.